Our 9,000-Year Love Affair With Booze

Alcohol isn’t just a mind-altering drink: It has been a prime mover of human culture from the beginning, fueling the development of arts, language, and religion.

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A Chinese newlywed toasts her guests with a traditional cup of rice wine. The drink has been consumed in China for at least 9,000 years; a chemical residue found in a jar of that age is the oldest proof of a deliberately fermented beverage. But the influence of alcohol probably extends even deeper into prehistory.

This story appears in the
February 2017 issue of
National Geographic magazine.

If you’re a beermaker in Germany, Martin Zarnkow is a guy you want to know. Students come to his department at the Technical University of Munich because it’s one of the few places in this nation of beer drinkers to get a degree in brewing science. Some of Germany’s biggest breweries come to Zarnkow to troubleshoot funky tastes, develop new beers, or just purchase one of his hundreds of strains of yeast. His lab is secured with coded door locks and filled with sophisticated chemical equipment and gene sequencers. But today he’s using none of that.

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A symposium today is a scholarly conference, but in ancient Greece it was an all-male, after-dinner drinking party. Guests drank wine from a cup called a
kylix, like this one from the fifth century B.C. A drinking master diluted the wine with water and filled each cup. If he did his job judiciously, and especially if Socrates was there, a symposium might well include learned conversation.

Instead I find him down the hall, hunched over an oven in the employee kitchen, poking what looks like a pan of mushy granola cookies with a black plastic spatula. The cookies are made from brewer’s malt—sprouted, toasted barley grains—mixed with wheat flour and a few spoonfuls of sourdough starter. Pouring a coffee, Zarnkow tells me that his plan today is to re-create beer from a 4,000-year-old Sumerian recipe.

Zarnkow, who started his career as a brewer’s apprentice, is also an eminent beer historian. He’s a big man with a full salt-and-pepper beard, ruddy cheeks, a booming voice, and a belly that strains the buttons on his short-sleeved plaid shirt. Put him in a brown habit and he’d be well cast as a medieval monk, the one in charge of stocking the abbey with barrels of ale. The former abbey next door, for example: Zarnkow’s building shares a hilltop, overlooking the Munich airport, with the Weihenstephan brewery, which was founded by Benedictine monks in A.D. 1040 and is the oldest continually functioning brewery in the world.

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In parts of South America the corn beer known as chicha has been a staple for thousands of years. Brewing it has traditionally been women’s work. A page from a 16th-century Spanish chronicle made in Peru shows a noblewoman serving chicha to an Inca emperor, who raises it to toast the sun god, Inti. Private Collection

You don’t have to be a regular at an Oktoberfest to know that Germany has a long history with beer. But Germany also has a long history with sausages. France started making wine in earnest only after it was conquered by the Romans (as did most of Europe) and has never looked back—but the French are also famously fond of cheese. For a long time that’s about how most historians and archaeologists have regarded beer and wine: as mere consumables, significant ones to be sure, but not too different from sausages or cheese, except that overconsumption of alcohol is a far more destructive vice. Alcoholic beverages were a by-product of civilization, not central to it. Even the website of the German Brewers’ Federation takes the line that beer was likely an offshoot of breadmaking by the first farmers. Only once the craft blossomed at medieval abbeys like Weihenstephan did it become worth talking about.

Zarnkow is one of a group of researchers who over the past few decades have challenged that story. He and others have shown that alcohol is one of the most universally produced and enjoyed substances in history—and in prehistory too, because people were imbibing alcohol long before they invented writing. Zarnkow’s Sumerian beer is very far from the oldest. Chemical analysis recently showed that the Chinese were making a kind of wine from rice, honey, and fruit 9,000 years ago. In the Caucasus Mountains of modern-day Georgia and the Zagros Mountains of Iran, grapes were one of the earliest fruits to be domesticated, and wine was made as early as 7,400 years ago.

All over the world, in fact, evidence for alcohol production from all kinds of crops is showing up, dating to near the dawn of civilization. University of Pennsylvania biomolecular archaeologist Patrick McGovern believes that’s not an accident. From the rituals of the Stone Age on, he argues, the mind-altering properties of booze have fired our creativity and fostered the development of language, the arts, and religion. Look closely at great transitions in human history, from the origin of farming to the origin of writing, and you’ll find a possible link to alcohol. “There’s good evidence from all over the world that alcoholic beverages are important to human culture,” McGovern says. “Thirty years ago that fact wasn’t as recognized as it is now.” Drinking is such an integral part of our humanity, according to McGovern, that he only half jokingly suggests our species be called Homo imbibens.

Today Zarnkow is trying to connect his students with those roots. The barley cookies are a vehicle for the sourdough, which contains the yeast that will make the magic happen. When the cookies are ready—dark brown on top, still a little soft in the middle—Zarnkow carries them from the kitchen to an upstairs lecture hall. There, in front of his class, he slides them into a huge glass pitcher, then scoops in more crushed barley malt and some milled emmer, an ancient grain, as the Sumerians would have done. The final ingredient: three quarts of tap water from a sink in the hallway. Zarnkow stirs the resulting slop with his kitchen spatula until it’s a uniform, yellowish beige, like bread dough.

It looks decidedly unappetizing. But by tomorrow, Zarnkow promises, this will be beer—a primitive, wild beer, one that people 5,000 or more years ago might have been intimately familiar with. “Mix three different ingredients with water, and that’s it,” he says. “Craft brewers today aren’t discovering anything new. Billions of people have brewed, over thousands of years.”

All through my visit I’ve been distracted by a rich, malt aroma wafting through the open windows from the brewery next door. It’s a primal, pleasant smell, and it taps into a part of my brain that makes me want to stop, sit down, inhale deeply, and take a seat in the nearest beer garden.

We Come Down From the Trees for Booze

The story of humanity’s love affair with alcohol goes back to a time before farming—to a time before humans, in fact. Our taste for tipple may be a hardwired evolutionary trait that distinguishes us from most other animals.

The active ingredient common to all alcoholic beverages is made by yeasts: microscopic, single-celled organisms that eat sugar and excrete carbon dioxide and ethanol, the only potable alcohol. That’s a form of fermentation. Most modern makers of beer, wine, or sake use cultivated varieties of a single yeast genus called Saccharomyces (the most common is S. cerevisiae, from the Latin word for “beer,” cerevisia). But yeasts are diverse and ubiquitous, and they’ve likely been fermenting ripe wild fruit for about 120 million years, ever since the first fruits appeared on Earth.

From our modern point of view, ethanol has one very compelling property: It makes us feel good. Ethanol helps release serotonin, dopamine, and endorphins in the brain, chemicals that make us happy and less anxious.

To our fruit-eating primate ancestors swinging through the trees, however, the ethanol in rotting fruit would have had three other appealing characteristics. First, it has a strong, distinctive smell that makes the fruit easy to locate. Second, it’s easier to digest, allowing animals to get more of a commodity that was precious back then: calories. Third, its antiseptic qualities repel microbes that might sicken a primate. Millions of years ago one of them developed a taste for fruit that had fallen from the tree. “Our ape ancestors started eating fermented fruits on the forest floor, and that made all the difference,” says Nathaniel Dominy, a biological anthropologist at Dartmouth College. “We’re preadapted for consuming alcohol.”

Robert Dudley, the University of California, Berkeley physiologist who first suggested the idea, calls it the “drunken monkey” hypothesis. The primates that ventured down out of the trees got access to a brand-new food source. “If you can smell the alcohol and get to the fruit faster, you have an advantage,” Dudley says. “You defeat the competition and get more calories.” The ones that stuffed themselves were the most likely to succeed at reproduction—and to experience (while eating) a gentle rush of pleasure in the brain. That buzz reinforced the appeal of the new lifestyle.

A truly drunken monkey, Dudley points out, would be an easy target for predators. In spite of widely reported anecdotes, there’s very little scientific evidence of animals in the wild ever getting enough alcohol from fermented fruit to exhibit drunken behavior. A satisfied glow is more likely. But that response to alcohol seems to be specific to humans and perhaps apes.

The reason may be a critical gene mutation that occurred in the last common ancestor of African apes and us; geneticists recently dated the mutation to at least 10 million years ago. This change in the ADH4 gene created an enzyme that made it possible to digest ethanol up to 40 times faster. According to Steven Benner, a co-author of the study and a biologist at the Foundation for Applied Molecular Evolution in Alachua, Florida, the new improved enzyme enabled our ancestors to enjoy more of the overripe bounty on the forest floor, without suffering ill effects.

“You could say we came out of the trees to get a beer,” Benner says. But the point wasn’t to get drunk. That would come much later, once we figured out how to make the stuff in quantity.

We Settle Down and Farm for Booze

Flash forward millions of years to a parched plateau in southeastern Turkey, not far from the Syrian border. Archaeologists there are exploring another momentous transition in human prehistory, and a tantalizing possibility: Did alcohol lubricate the Neolithic revolution? Did beer help persuade Stone Age hunter-gatherers to give up their nomadic ways, settle down, and begin to farm?

The ancient site, Göbekli Tepe, consists of circular and rectangular stone enclosures and mysterious T-shaped pillars that, at 11,600 years old, may be the world’s oldest known temples. Since the site was discovered two decades ago, it has upended the traditional idea that religion was a luxury made possible by settlement and farming. Instead the archaeologists excavating Göbekli Tepe think it was the other way around: Hunter-gatherers congregated here for religious ceremonies and were driven to settle down in order to worship more regularly.

Nestled inside the walls of some smaller enclosures are six barrel- or trough-shaped stone vessels. The largest could hold 40 gallons of liquid. The archaeologists suggest that they were used to brew a basic beer from wild grasses.

Alcohol Through the Ages

Some 10 million years ago, a shared ancestor of humans and African apes evolved an enzyme that could more rapidly digest the alcohol in fermented fruit. That set the biological stage for the past 10,000 years—in which people all over the world have made alcoholic beverages by fermenting sugars in whatever fruits were available and even by finding ways to ferment starchy grains and roots.

Drinking locally, trading globally

In early civilizations, fermented beverages were made from whatever wild plants were available locally and later from domesticated plants. As trade between civilizations grew, technology and techniques for brewing and winemaking spread throughout the ancient world.

5400 b.c.

4000 b.c.

NORTH

AMERICA

ASIA

9

EUROPE

7500 b.c.

8

3

1000 b.c.

2

6

4

5

5

6000 b.c.

7

4000 b.c.

AFRICA

1

SOUTH

AMERICA

Exchange of

information about

fermented

beverages

Zones of early

fermented

beverage

experimentation

Searching for proof

Firm evidence for early consumption of alcohol comes from analysis of ancient chemical residues; the earliest so far is from China. Other dates on the map are estimates based on when a plant or crop later used to make alcohol first appears in the archaeological record.

Some 10 million years ago, a shared ancestor of humans and African apes evolved an enzyme that could more rapidly digest the alcohol in fermented fruit. That set the biological stage for the past 10,000 years—in which people all over the world have made alcoholic beverages by fermenting sugars in whatever fruits were available and even by finding ways to ferment starchy grains and roots.

4000 b.c.

5400 b.c.

9

EUROPE

NORTH

AMERICA

ASIA

6000 b.c.

8

1000 b.c.

3

2

6

4

5

5

7

AFRICA

1

Zones of early

fermented beverage

experimentation

SOUTH

AMERICA

Exchange of

information about

fermented beverages

Drinking locally,

trading globally

In early civilizations, fermented beverages were made from whatever wild plants were available locally and later from domesticated plants. As trade between civilizations grew, technology and techniques for brewing and winemaking spread throughout the ancient world.

Searching for proof

Firm evidence for early consumption of alcohol comes from analysis of ancient chemical residues; the earliest so far is from China. Other dates on the map are estimates based on when a plant or crop later used to make alcohol first appears in the archaeological record.

Earliest evidence of grape wine, at Hajji Firuz in the Zagros Mountains of Iran

Analyzing residues from several of those tubs, Zarnkow found evidence of oxalate, a crusty, whitish chemical left behind when water and grain mix. One vessel contained the shoulder bone of a wild ass, just the right size and shape to stir a foaming, fermenting broth of grain and water. The whole hilltop at Göbekli Tepe is filled with hundreds of thousands of animal bones, mostly gazelle and barbecue-ready cuts of aurochs, a prehistoric cousin to the cow.

Add it all together, and you have the makings of an impressive feast, enough to attract hundreds of hunter-gatherers to that prominent hill. One purpose of the alcohol may have been the same one that leads South American shamans today to take hallucinogens: to induce an altered state that puts them in touch with the spirit world. But researchers here think something else was going on too. The organizers of the feast, they say, were using the barbecue and the booze brewed from wild grains as a reward. Once the partygoers arrived, they pitched in to erect the site’s massive pillars, which weigh up to 16 tons.

2010 per capita consumption, age 15+

Alcohol content of beverages, in quarts

Spirits

Beer

Wine

Other

Unrecorded

Palm wine, mead, and other commercially available beverages

Alcoholic beverages outside of government control, such as homemade brews and moonshine

WORLD

6.9

Africa

5.3

ASia

5.5

North America

8.7

South America

8.9

Australia/Oceania

10.7

Europe

12.8

12.8

10.7

2010 per capita consumption, age 15+

Alcohol content of beverages, in quarts

8.9

8.7

Unrecorded

Alcoholic beverages outside of government control, such as homemade brews and moonshine

6.9

5.5

Other

5.3

Palm wine, mead, and other commercially

available beverages

Spirits

Wine

Beer

WORLD

Africa

ASia

North

America

South

America

Australia/

Oceania

Europe

The Drinking World

People in wealthy regions with long drinking traditions, such as Europe, tend to drink the most. Abstainers are more often found in the Middle East and Southeast Asia, where laws or tradition limit consumption.

The outlines of the deal have changed little in the thousands of years since. “If you need someone to help you move, you buy them pizza and a couple of beers,” says German Archaeological Institute researcher Jens Notroff.

The idea that’s gaining support at Göbekli Tepe was first proposed more than half a century ago: Beer, rather than bread, may have been the inspiration for our hunter-gatherer ancestors to domesticate grains. Eventually, simply harvesting wild grasses to brew into beer wouldn’t have been enough. Demand for reliable supplies pushed humans first to plant the wild grasses and then over time to selectively breed them into the high-yielding barley, wheat, and other grains we know today. Some of the earliest evidence of domesticated grain—an ur-wheat called einkorn—comes from a site a few dozen miles away from Göbekli Tepe. The coincidence is suggestive.

But proof is elusive. Zarnkow is quick to admit that oxalate proves that grain was present in the stone tubs at Göbekli Tepe, but not that the grain was fermented. It’s possible, he says, that the tubs were used to make gruel to feed the workers, not beer to get them buzzed.

Patrick McGovern acknowledges the uncertainty but still says the beer-before-bread theory is solid. In 2004 he published evidence of a cocktail made of rice, hawthorn berries, honey, and wild grapes at Jiahu, a site in China just a few thousand years younger than Göbekli Tepe. The people there had only recently made the transition to farming. Yet the combination of ingredients, plus the presence of tartaric acid, a key chemical signature of wine, convinces McGovern that Jiahu farmers were already concocting sophisticated mixed beverages: It’s the earliest evidence for beer, wine, and mead, all in one.

“The domestication of plants is driven forward by the desire to have greater quantities of alcoholic beverages,” McGovern says. “It’s not the only factor driving forward civilization, but it plays a central role.”

We Drink It for Our Health

Alcoholic beverages, like agriculture, were invented independently many different times, likely on every continent save Antarctica. Over the millennia nearly every plant with some sugar or starch has been pressed into service for fermentation: agave and apples, birch tree sap and bananas, cocoa and cassavas, corn and cacti, molle berries, rice, sweet potatoes, peach palms, pineapples, pumpkins, persimmons, and wild grapes. As if to prove that the desire for alcohol knows no bounds, the nomads of Central Asia make up for the lack of fruit and grain on their steppes by fermenting horse milk. The result, koumiss, is a tangy drink with the alcohol content of a weak beer.

Alcohol may afford psychic pleasures and spiritual insight, but that’s not enough to explain its universality in the ancient world. People drank the stuff for the same reason primates ate fermented fruit: because it was good for them. Yeasts produce ethanol as a form of chemical warfare—it’s toxic to other microbes that compete with them for sugar inside a fruit. That antimicrobial effect benefits the drinker. It explains why beer, wine, and other fermented beverages were, at least until the rise of modern sanitation, often healthier to drink than water.

What’s more, in fermenting sugar, yeasts make more than ethanol. They produce all kinds of nutrients, including such B vitamins as folic acid, niacin, thiamine, and riboflavin. Those nutrients would have been more present in ancient brews than in our modern filtered and pasteurized varieties. In the ancient Near East at least, beer was a sort of enriched liquid bread, providing calories, hydration, and essential vitamins.

At Tall Bazi, a site in northern Syria, a German excavation revealed a clutch of about 70 houses overlooking the Euphrates River that were abandoned during a sudden fire almost 3,400 years ago. The long-ago catastrophe was a blessing for archaeologists: The fire forced Tall Bazi’s residents to flee in the middle of daily tasks such as cooking. It thus captured for all time a moment in the town’s everyday life.

In each house, usually close to the front door, the excavators found a huge, 50-gallon clay jar sunk into the floor. Chemical analysis—by Zarnkow again—revealed traces of barley and thick crusts of oxalate in the jars. In effect, each of Tall Bazi’s houses had its own nanobrewery.

By 3150 B.C., long before the fire that wiped out Tall Bazi, the ancient Egyptians had progressed beyond home brew: They were maintaining industrial-scale breweries of the sort that were eventually used to supply workers building the great Pyramids at Giza. Beer was such a necessity in Egypt that royals were buried with miniature breweries to slake their thirst in the afterlife. In ancient Babylon beer was so important that sources from 500 B.C. record dozens of types, including red beer, pale beer, and dark beer.

Indirectly, we may have the nutritional benefits of beer to thank for the invention of writing, and some of the world’s earliest cities—for the dawn of history, in other words. Adelheid Otto, an archaeologist at Ludwig-Maximilians University in Munich who co-directs excavations at Tall Bazi, thinks the nutrients that fermenting added to early grain made Mesopotamian civilization viable, providing basic vitamins missing from what was otherwise a depressingly bad diet. “They had bread and barley porridge, plus maybe some meat at feasts. Nutrition was very bad,” she says. “But as soon as you have beer, you have everything you need to develop really well. I’m convinced this is why the first high culture arose in the Near East.”

We Always Go Too Far

And then, of course, there is the other side of the story. There are the lengths to which people throughout history have gone to go on a bender.

Before the Celtic ancestors of the French learned to produce wine themselves, they imported it from the Greeks, Etruscans, and Romans. In a wheat field at the end of a winding mountain road in central France, at an archaeological site called Corent, I get a taste of this dependency. My guide is Matthieu Poux, a Franco-Swiss archaeologist with a crew cut, blue aviator shades that match his shirt, and a firm handshake. All around us the extinct volcanoes of France’s Massif Central stab the sky.

At Corent, Poux leads some 50 French archaeologists and students who are uncovering the foundations of a major Celtic ceremonial center and regional capital. In the second and first centuries B.C. it was home to as many as 10,000 people. The town had a marketplace, a temple, taverns, a theater, and hundreds of houses.

Corent, Poux says, is a vivid example of alcohol’s role as cultural glue, social lubricant, and status symbol—and inciter of violence. There’s no need for sophisticated analysis to determine what the inhabitants preferred to pour. Around 140 B.C., eight decades before Julius Caesar’s invasion, Corent’s elites developed a ferocious taste for Roman wine. The evidence, in the shape of shattered clay wine jars, or amphorae, is so abundant that it crunches underfoot as Poux leads me across the site. Archaeologists have uncovered at least 50 tons of broken amphorae here; Poux estimates that 500 tons more remain on the hilltop.

Bending down, he plucks a palm-size chunk of fired clay flecked with black volcanic glass from the dirt and hands it to me. “We have millions of amphora sherds, all imported from Italy,” he says. “This one has obsidian in it—you can tell it came from the countryside near Mount Vesuvius.”

Roman vintners, whose elite Roman clients preferred white wines, tended vast plantations of red wine grapes for the Celtic market; traders moved the wine across the Mediterranean, in ships that carried up to 10,000 amphorae each, and then sent it north on small river barges. By the time it reached Corent months later, its value had multiplied a hundredfold. One contemporary claimed the thirsty Celts would trade a slave for a single jar.

Wine was the focus of elaborate rituals that cemented the status of the tribal leaders. Things often got rowdy. “The ceremonies were pompous, official—and brutal too, with sacrificial victims and sword fights breaking out over portions of meat,” Poux says. “Warriors drank heavily before battle and went into battle drunk.” Amphorae weren’t merely opened; they were beheaded with swords. By paving their streets with the broken jars, Poux says, the rulers of Corent flaunted their wealth and power.

By his calculations, the Celts living here went through 50,000 to 100,000 wine jars over the course of a century, the equivalent of 28,000 bottles a year of expensive, imported Italian red. “And wine was primarily drunk by elites,” Poux says. “We have to assume lots more beer and mead was drunk by commoners.”

Still, by today’s standards, the quantities may not sound impressive. The modern world is awash in booze, and ever since the perfection of distillation in the Middle Ages, we’ve consumed a lot of it in concentrated form. Worldwide, people age 15 and over average about a drink a day—or more like two if you include only drinkers, because about half of us have never touched a drop. In the United States, alcohol abuse kills 88,000 Americans and costs $249 billion a year, according to estimates by the Centers for Disease Control and Prevention.

Millions of years ago, when food was harder to come by, the attraction to ethanol and the brain chemistry that lit up to reward the discovery of fermented fruit may have been a critical survival advantage for our primate ancestors. Today those genetic and neurochemical traits may be at the root of compulsive drinking, says Robert Dudley, whose father was an alcoholic.

Throughout history, ethanol’s intoxicating power has made it an object of concern—and sometimes outright prohibition. And through the ages, says Rod Phillips, author of Alcohol: A History, most societies have struggled to strike a balance: “Allow people to drink because it makes them happy and is a gift from the gods, but prevent them from drinking too much.”

The ancient Greeks were a good example. A crucial part of their spiritual and intellectual life was the symposium fueled by wine—within limits. Mixing wine with water in a decorated vessel called a krater, Greek hosts served their (exclusively male) guests a first bowl for health, another for pleasure, and a third for sleep. “When this bowl is drunk up, wise guests go home,” the comic poet Eubulus warned in the fourth century B.C., according to one translation. “The fourth bowl is ours no longer, but belongs to violence; the fifth to uproar; the sixth to drunken revel; the seventh to black eyes. The eighth is the policeman’s; the ninth belongs to biliousness; and the 10th to madness and the hurling of furniture.”

A Taste of Our History

It’s been 24 hours since Zarnkow mashed together barley, bread, and milled grain in a widemouthed laboratory pitcher. The mixture spent the night sitting on a table next to his desk, covered by a paper plate.

When Zarnkow flicks on the lights, I can immediately see that the slop has come alive, thanks to yeast from the sourdough. Muddy sediment at the bottom of the pitcher resembles wet muesli. Every few seconds, a large bubble of carbon dioxide percolates to the top through a scummy layer of foam. A translucent gold liquid, resembling the wheat beer brewed in massive steel tanks at the brewery next door, rests in the middle.

Zarnkow says the inspiration for the brew came from a 5,000-year-old song. A hymn to Ninkasi, the Sumerian goddess of beer, it sounds a lot like the technical brewing manuals lining Zarnkow’s office shelves. “Ninkasi, when your rising bread is formed with the noble spatula, it has an aroma like from mellow honey,” one recent translation reads. “To let the fermenting vat produce loud sounds, you place it appropriately on a sublime collector vat.”

He and I look at the bubbling pitcher, in my case a little uneasily. “There’s no added carbon dioxide, no hops. It’s not filtered. It’s not to European tastes,” Zarnkow warns me, managing my expectations as he strains some Sumerian home brew through a coffee filter. “But back then, the alternative wasn’t tea or coffee or milk or juice or soft drinks. This is much more tasty than warm water filled with microorganisms.”

I pour a few fingers into a flimsy plastic cup. Bits of grain float to the top.

I take a cautious sniff.

I sip.

The beer is both tart and sweet, bready with a hint of sour apple juice at the end. It’s … actually pretty good. If I close my eyes, I can almost imagine it changing the world.

Photographer
Brian Finke has shot stories for the magazine on the science of taste, food waste, and meat.
Andrew Curry’s last feature was on Trajan’s Column in Rome. He lives in Berlin.

An earlier version of the graphic in this story misleadingly referred to pepper berry wine as “strong.” Although the beverage has a strong, pleasantly sharp taste, its alcohol content is rather mild. The graphic also incorrectly described cacao wine as a frothy beverage served from a pot. This description is for a later Mesoamerican beverage made from the cacao bean, not the fruit. The graphic also originally stated that ancient brewers chewed cassava first to make cassava beer. However, cassava was peeled, diced, and boiled—and then chewed. Cassava is poisonous if not prepared correctly.